Steam return?

You can return a game within two weeks if you've played it for less than two hours. But I'm wondering if there's a limit. I'm very picky about games, so I love this two-hour rule because it gives me plenty of time to try them out. But what happens if I buy several games at once on the same day and return them all because, for example, I don't like them? How does Steam react to something like that? Do they refund everything, or do they just say no at some point? I don't want to be forced to pay €30 for a game I don't like and would rather return.